Pardon my stupidity, but do you mean like this:

package Stuff::DBI;
use base 'Class::DBI::BaseDSN';

package Stuff::Item;
use base 'Stuff::DBI';
__PACKAGE__->set_up_table('item');
__PACKAGE__->has_a(categoryId => 'Stuff::Category');

package Stuff::Category;
use base 'Stuff::DBI';
__PACKAGE__->set_up_table('category');
__PACKAGE__->has_a(departmentId => 'Stuff::Department');

package Stuff::Department;
use base 'Stuff::DBI';
__PACKAGE__->set_up_table('department');

package main;
Stuff::DBI->set_db('Main', 'dbi:mysql:dbname', 'gryphon', 'password');

my $item = Stuff::Item->retrieve(1);
print $item->name, "\n";
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When I run this, I get a "Can't locate object method 'set_up_table' via package 'Stuff::Item' blah blah" when I run this. What am I doing wrong?